TOC is Tournament of Champions. I was the biggest aerobatic contest in the world celebrated once every two years or yearly sometimes. Last one was on 2002, and there haven't been any others since the person that hosted the TOC died, unfortunately.
When they r efer to a 3W engine as TOC, its just the engine model. The TOC model is just a little more powerful than the Classic series one.
Hope to have helped you clear up a bit.
Vic